JP6135240B2 - Photoelectric converter and light detection method - Google Patents

Description

  The present invention relates to a photoelectric converter and a light detection method.

  Photodetectors such as infrared detectors are useful as light detection units such as heat source detection, temperature measurement, specific gas detection, and sensors for night vision devices. In addition, a technique for detecting light in a wavelength region such as an infrared region using them is particularly useful.

  The photodetector includes a single photodetector or a one-dimensional or two-dimensional array according to the application. As an example of such a photodetector, there is a quantum dot infrared detector (QDIP) including a quantum dot in a light absorption layer.

QDIP has a structural feature that a semiconductor having a larger band gap than the material constituting the quantum dot surrounds the quantum dot three-dimensionally. For this reason, electrons and holes inside the quantum dot have discrete energy levels (hereinafter simply referred to as levels) due to the strong confinement effect of the semiconductor.
QDIP can detect infrared rays having energy corresponding to the energy difference between subbands by using subband levels of a plurality of electrons in the conduction band among these levels.

  QDIP can detect the amount of light for each of a plurality of desired wavelength spectra in accordance with the detection target. For example, in heat detection, a spectrum depending on temperature can be detected. In gas detection, a specific spectrum depending on the gas composition can be detected.

  Non-Patent Document 1 or Patent Document 1 discloses an infrared detector having sensitivity in a plurality of wavelength bands by including QDIP. Non-Patent Document 1 has a dot-in-well structure in which quantum dots are present in a quantum well, and detects light in a three-wavelength band having center wavelengths of 23.2, 8.5, and 3.8 μm, respectively. QDIP is disclosed.

  These three wavelength bands correspond to the transition energy between the bound levels of InAs quantum dots, between the bound levels of InAs quantum dots and InGaAs quantum wells, and between the bound levels of InAs quantum dots and the continuous levels of the GaAs intermediate layer, respectively. It corresponds to the wavelength to be.

  FIG. 12 shows an infrared detector that is a kind of QDIP having two light absorption layers or photoelectric conversion layers having different absorption wavelengths. In FIG. 12, the infrared detector 20 includes a semiconductor substrate 1, a first light absorption layer 10, and a second light absorption layer 11. The first light absorption layer 10 is located above the semiconductor substrate 1 in the drawing.

  The second light absorption layer 11 is located above the first light absorption layer 10 in the drawing. The first light absorption layer 10 includes a contact layer 2, a photoelectric conversion layer 4, and a contact layer 5. The second light absorption layer 11 includes a photoelectric conversion layer 7 and a contact layer 8. The electrodes 3, 6 and 9 are in contact with the contact layers 2, 5 and 8, respectively. The infrared detector 20 receives infrared rays 107 from below in the figure.

  The infrared detector described in Patent Document 1 is a kind of QDIP in FIG. The infrared detector has two light absorption layers including quantum dots whose planar shape is elliptical. In such an infrared detector, the major axis direction of the quantum dots contained in the first light absorption layer and the major axis direction of the quantum dots contained in the second light absorption layer are orthogonal to each other. Such a detector utilizes the polarization dependence caused by the directionality of these quantum dots. For this reason, it is possible to switch and detect light of two or more wavelength bands.

Japanese Patent No. 4842291

S. Krishna, et al., “APPLIED PHYSICS LETTERS”, 2003, Vol. 83, No. 14, p. 2745-2747

  QDIP disclosed in Non-Patent Document 1 is an excellent one having sensitivity to three wavelengths. However, there is a problem that signals for each wavelength cannot be distinguished and can only be extracted as the sum of signals in three wavelength bands.

  In QDIP disclosed in Patent Document 1, the major axis directions of the quantum dots of the first light absorption layer and the second light absorption layer are orthogonal to each other based on a technique called sublattice exchange. That is, the QDIP realizes sublattice exchange by providing a Si layer composed of several atoms between two GaAs layers constituting the first and second light absorption layers.

  The QDIP is an excellent one having sensitivity in a wavelength band of two wavelengths or three wavelengths or more. However, the QDIP manufacturing process requires a precise thickness control technique at the level of one atomic layer. For this reason, it is not easy to manufacture in any field. Further, since the above QDIP utilizes orthogonal light deflection states, it is not suitable for use in detecting two or more wavelengths having the same polarization direction.

  An object of the present invention is to provide a photoelectric converter capable of selectively photoelectrically converting light in a plurality of wavelength bands with a simple structure, and a light detection method using the photoelectric converter.

  The photoelectric converter of the present invention includes a semiconductor substrate, a light absorption layer, an optical resonator, and a modulation unit that modulates a resonance wavelength band of the optical resonator. The light absorption layer has one or more quantum confinement structures selected from the group consisting of quantum dots, quantum wires, and quantum wells. The modulation means includes an input unit that receives an applied voltage from a voltage source.

  The light detection method of the present invention includes the photoelectric converter, a modulation voltage source connected to the input unit, a detection voltage source connected to the light absorption layer, and an ammeter connected to the light absorption layer. , To detect light.

  The light detection method of the present invention includes a modulation step of modulating the resonance wavelength band by generating or changing an applied voltage to the modulation means with the modulation voltage source, and light reception of receiving light with the photoelectric converter. And an optical resonance process for causing the light to resonate within the optical resonator.

  The light detection method of the present invention further includes a light absorption step of absorbing the resonated light in the quantum confinement structure, and applying a voltage to the light absorption layer with the detection voltage source to thereby absorb the absorbed light. A photoelectric conversion step of photoelectrically converting the light absorption layer to generate a current, and a detection step of detecting the current by the ammeter;

  According to the present invention, it is possible to provide a photoelectric converter capable of selectively photoelectrically converting light in a plurality of wavelength bands with a simple structure, and a light detection method using the photoelectric converter.

It is the schematic of the photoelectric converter which concerns on 1st Embodiment. It is a structure sectional view of a photoelectric converter concerning a 1st embodiment. It is a structure sectional view of the photoelectric conversion layer concerning a 1st embodiment. It is a schematic diagram showing the principle of operation of the light absorption layer concerning a 1st embodiment. It is a schematic diagram showing the principle of operation of the light absorption layer concerning a 1st embodiment. It is a schematic diagram which shows the detection wavelength sensitivity of the photoelectric converter which concerns on 1st Embodiment. It is a schematic diagram which shows the detection wavelength sensitivity of the photoelectric converter which concerns on 1st Embodiment. It is a graph showing the detection spectrum of the photoelectric converter before and behind refractive index modulation. It is the schematic of the photoelectric converter which concerns on 2nd Embodiment. It is a schematic diagram showing the resonance spectrum of the 1st resonator which concerns on 2nd Embodiment. It is a schematic diagram showing the resonance spectrum of the 2nd resonator which concerns on 2nd Embodiment. It is a schematic diagram showing the resonance spectrum of the photoelectric converter which concerns on 2nd Embodiment. It is a schematic diagram showing the absorption spectrum of the light absorption layer which concerns on 2nd Embodiment. It is a schematic diagram showing the detection spectrum of the photoelectric converter which concerns on 2nd Embodiment. It is a schematic diagram showing the resonance spectrum of the 1st resonator which concerns on 2nd Embodiment. It is a schematic diagram showing the resonance spectrum of the 2nd resonator which concerns on 2nd Embodiment. It is a schematic diagram showing the resonance spectrum of the photoelectric converter which concerns on 2nd Embodiment. It is a schematic diagram showing the absorption spectrum of the light absorption layer which concerns on 2nd Embodiment. It is a schematic diagram showing the detection spectrum of the photoelectric converter which concerns on 2nd Embodiment. It is the schematic of the photoelectric converter which concerns on 3rd Embodiment. It is the schematic of the photoelectric converter which concerns on 4th Embodiment. It is the schematic of the photoelectric converter which concerns on a comparative example.

  Hereinafter, embodiments of the photodetector and the light detection method of the present invention will be described focusing on the infrared detector, the photoelectric converter included in the infrared detector, and the infrared detection method.

[First embodiment]
1. Configuration In FIG. 1, the photoelectric converter 100 includes a semiconductor substrate 101, a light absorption layer 102, a light modulation layer 103, a resonator 106, a lower electrode 214, and an upper electrode 215. The light absorption layer 102 has a photoelectric conversion function. The light absorption layer 102 is located above the semiconductor substrate 101 in the drawing. The light modulation layer 103 is modulation means for modulating the resonance wavelength band of the resonator 106. The light modulation layer 103 is located above the light absorption layer 102 in the drawing.

  The resonator 106 is an optical resonator. The resonator 106 includes a first reflective film 104 positioned below the semiconductor substrate 101 in the drawing. The resonator 106 further includes a second reflective film 105 positioned above the light modulation layer 103 in the drawing.

  The lower electrode 214 and the upper electrode 215 receive an applied voltage from a voltage source (modulation voltage source) as an input to the light modulation layer 103. The light modulation layer 103, the lower electrode 214, and the upper electrode 215, as modulation means, modulate the resonance wavelength band of the resonator 106 according to the generation or change of the applied voltage.

  The infrared rays 107 enter the photoelectric converter 100 from below in the figure. Thereafter, part of the infrared light 107 is reflected by the second reflective film 105 regardless of the specific wavelength. Infrared light 107 reflected by the second reflective film 105 may be partially reflected by the first reflective film 104 regardless of a specific wavelength.

  Among the infrared rays 107, light having a specific wavelength becomes a standing wave in a region sandwiched between the first reflective film 104 and the second reflective film 105. The specific wavelength of the light to be a standing wave is selected by the distance between the first reflective film 104 and the second reflective film 105, that is, the length of the resonator 106, and the refractive index between the reflective films.

  Therefore, when the first reflective film 104 and the second reflective film 105 are, for example, metal films, most of light other than a specific wavelength that enters the resonator 106 is transmitted through the first reflective film 104 and the second reflective film 105. Although reflected, it is difficult to become a standing wave. For this reason, only light of a specific wavelength can be detected efficiently.

  Further, the first reflective film 104 or the second reflective film 105 can be a multilayer film for distributed reflection. In such a case, the first reflective film 104 or the second reflective film 105 efficiently reflects only the specific wavelength and light in the vicinity of the wavelength, while transmitting other light. For this reason, most of light other than a specific wavelength is still less likely to be a standing wave.

  The light having the specific wavelength resonates inside the first reflective film 104 and the second reflective film 105 and becomes a standing wave. For this reason, the resonant wavelength is limited by the standing wave standing in the space between the two reflecting films in the infrared ray 107. This corresponds to the limitation of the wavelengths of infrared rays 107 that are accumulated over time or the distance traveled by light within the region is limited. Therefore, the photodetector having the photoelectric converter 100 can detect light of a specific wavelength that has become a standing wave as described above.

  An infrared detector 200 shown in FIG. 2A includes the photoelectric converter 100 shown in FIG. The infrared detector 200 further includes a lower electrode 206, an upper electrode 207, a voltage source 208 (detection voltage source), an ammeter 209, and a voltage source 216 (modulation voltage source).

  FIG. 2A shows the light absorption layer 102 and the light modulation layer 103 in the photoelectric converter 100 in detail. The light absorption layer 102 has a semiconductor stacked structure including quantum dots. The light absorption layer 102 has a discrete absorption wavelength band having two or more maximum wavelengths as described below. Hereinafter, a specific absorption wavelength band corresponding to a specific maximum wavelength included in the absorption wavelength band may be referred to as an absorption wavelength peak.

  The light absorption layer 102 includes a buffer layer 201, a lower contact layer 202, a photoelectric conversion layer 220, and an upper contact layer 205. The buffer layer 201 is made of the same semiconductor material as that of the semiconductor substrate 101, and has a function of alleviating minute irregularities on the surface of the semiconductor substrate 101 and improving the crystal quality of the upper layer.

The lower contact layer 202 is made of a conductive semiconductor including a semiconductor doped with an n-type dopant, and is positioned above the buffer layer 201 in the drawing.
The photoelectric conversion layer 220 includes an intermediate layer 203, a quantum dot layer 204, and a strain relaxation layer 217. The intermediate layer 203 is made of an i-type semiconductor and is located above the lower contact layer 202 in the drawing. As the i-type semiconductor, a semiconductor having a lattice constant different from that of the quantum dot layer 204 is preferable. Specifically, GaAs, InGaAs, or AlGaAs is preferable.

  When the intermediate layer 203 is made of such a semiconductor, it can be provided with desired quantum dots described later. For this reason, the light absorption layer 102 or the photoelectric conversion layer 220 can have a desired absorption wavelength peak by including such quantum dots. The thickness of the intermediate layer 203 is preferably 10 to 100 nm.

  When the intermediate layer 203 is GaAs, the thickness is preferably 50 nm. Since the intermediate layer 203 has such a thickness, distortion of the quantum dots is relieved, so that multilayer quantum dots can be stacked. In addition, the photoelectric conversion layer 220 may include quantum dots that are uniformly stacked. Uniformly stacked quantum dots have small quality differences between adjacent quantum dot layers.

  The quantum dot layer 204 is positioned above the lowermost intermediate layer 203 in the drawing. The quantum dot layer 204 is preferably made of a semiconductor having a lattice constant different from that of the semiconductor of the intermediate layer 203. Specifically, InAs, InGaAs, or InSb is preferable. By having such a semiconductor material, the photoelectric conversion layer 220 can have a desired absorption wavelength peak.

  The quantum dot layer 204 preferably has a three-dimensional island shape and has a quantum dot called a SK (Transki-Krastanov) mode. The diameter of the quantum dots in the quantum dot layer 204 is preferably designed according to the detection wavelength.

  In this embodiment, in order to detect the mid-infrared, the quantum dot diameter of the quantum dot layer 204 is preferably 20 to 40 nm. The height of the quantum dots is preferably 5 to 20 nm.

  When the quantum dot layer 204 includes InAs quantum dots, the height is preferably 5 to 10 nm and the size is preferably 20 to 30 nm. When the quantum dots have such a size or shape, the photoelectric conversion layer 220 can have a desired absorption wavelength peak.

The number density of quantum dots per square centimeter of the quantum dot layer 204 is preferably about 10 ⁹ to 10 ¹¹ , and preferably 10 ¹⁰ from the viewpoint of efficiently producing a sensitive detector. When the light absorption layer 102 or the photoelectric conversion layer 220 includes the quantum dot layer 204, the infrared detector 200 can detect a current due to photoelectric conversion at a desired absorption wavelength peak. Details of the configuration of the quantum dot layer and the operation principle of the light absorption layer related to the quantum dot will be described later.

  The strain relaxation layer 217 is located above the lowermost quantum dot layer 204 in the drawing. The strain relaxation layer 217 is preferably provided separately from the intermediate layer in order to relax the accumulation of strain accompanying the formation of the quantum dots and to stack a plurality of quantum dot layers.

  The strain relaxation layer 217 is preferably made of a semiconductor different from the semiconductor of the quantum dot layer 204 in order to control the wavelength characteristics of the photoelectric conversion layer according to the thickness and composition. Further, since the strain relaxation layer 217 has a material different from that of the quantum dot layer 204, the quantum dot layer 204 operates as a quantum dot. When the strain relaxation layer 217 has the same material as the quantum dot layer 204, the layer functions as a quantum well.

  The strain relaxation layer 217 is preferably made of a semiconductor different from the semiconductor of the intermediate layer 203 in order to control the wavelength characteristics of the photoelectric conversion layer by the thickness and composition. Specifically, InGaAs, AlGaAs, or GaAs is preferable.

  The strain relaxation layer 217 preferably has a thickness of 5 to 10 nm corresponding to 1 to 2 times the height of the quantum dot layer in order to three-dimensionally relax local strain due to the quantum dots. Further, since the strain relaxation layer 217 can also be a quantum well, there is a possibility of affecting the absorption spectrum of the light absorption layer. Therefore, it is preferable to have a thickness equal to or greater than the height of the quantum dots from the viewpoint of wavelength control.

  The next intermediate layer 203 is located above the strain relaxation layer 217. The photoelectric conversion layer 220 preferably further includes a repetition of a layer having the quantum dot layer 204, the strain relaxation layer 217, and the intermediate layer 203 in the above order.

  By repeatedly arranging such layers, light can be efficiently absorbed. The photoelectric conversion layer 220 preferably has about 10 to 20 repetitions of such layers. By being within the range where the layers are repeated, light sufficient to detect the intensity of the specific wavelength can be absorbed.

  The upper contact layer 205 is made of a semiconductor doped with an n-type dopant, and is located above the uppermost intermediate layer 203 in the drawing. As described above, the light absorption layer 102 includes the plurality of quantum dot layers 204, so that the infrared absorption efficiency of the light absorption layer 102 is improved.

FIG. 2B shows details of the configuration of the quantum dot layer. The photoelectric conversion layer 220 has a first quantum dot and a second quantum dot. The first quantum dot layer 204 ₁ having a first quantum dot is located above in Fig intermediate layer 203. Strain reducing layer 217 is located above the first in view of the quantum dot layer 204 _1.

Another intermediate layer 203 is located above the strain relaxation layer 217 in the figure. Second quantum dot layer 204 ₂ having a second quantum dot is located above in view of the intermediate layer 203. Another strain reducing layer 217 is located above the second in view of the quantum dot layer 204 _2. Still another intermediate layer 203 is located above the strain relaxation layer 217 in the figure. The photoelectric conversion layer 220 includes a repetition of such a multilayer structure.

The second quantum dot is similar in shape to the first quantum dot and is smaller than the first quantum dot. Therefore, in the photoelectric conversion layer 220. yields a different specific absorption wavelength band, the first quantum dot layer 204 ₁ and the second quantum dot layer 204 ₂ alternately and repeatedly arranged.

  Arbitrary things can be selected as a size, shape, or material of a quantum dot which quantum dot layer 204 has. Furthermore, between the plurality of quantum dot layers 204, the size and shape, the size and material, or the quantum dots having different shapes and materials may be included. Furthermore, between the plurality of quantum dot layers 204, each of the size, shape, and material may have different quantum dots.

  The light absorption layer 102 includes, for example, a photoelectric conversion layer 220 having first quantum dots and second quantum dots, and two contact layers including a lower contact layer 202 and an upper contact layer 205. That is, the photoelectric conversion layer 220 is preferably located between the two contact layers.

  In addition, contact layers other than the two contact layers are not located in the photoelectric conversion layer 220, and the contact layers are preferably located outside the photoelectric conversion layer 220. Since the photoelectric conversion layer 220 has the above-described configuration, the light absorption layer 102 has a discrete absorption wavelength band having the same maximum number of wavelengths as the type of the quantum dot layer.

  Returning to FIG. 2A, the description of the infrared detector 200 of this embodiment will be continued. In FIG. 2A, the lower contact layer 202 is in contact with the lower electrode 206 on the upper surface in the drawing. In the portion where the lower contact layer 202 and the lower electrode 206 are in contact, the intermediate layer 203, the quantum dot layer 204, or the strain relaxation layer 217 is not in contact with the upper surface of the lower contact layer 202.

  In the present embodiment, the upper contact layer 205 is in contact with the upper electrode 207 on the upper surface in the drawing. In a portion where the upper contact layer 205 and the upper electrode 207 are in contact, a buffer layer 218 described later is not in contact with the upper surface of the upper contact layer 205.

  The voltage source 208 can be connected to the lower electrode 206 and the upper electrode 207. By connecting the voltage source 208 to each electrode, a desired voltage is applied between the lower contact layer 202 and the upper contact layer 205.

  When the voltage source 208 applies a voltage to the light absorption layer 102, the light absorption layer 102 absorbs the incident infrared rays 107, thereby changing into a photocurrent flowing from the upper electrode 207 to the lower electrode 206 in the light absorption layer 102. Occurs. The ammeter 209 detects the change in photocurrent through the circuit.

  In the present embodiment, the light modulation layer 103 has a structure in which semiconductors are stacked. The semiconductor includes a semiconductor quantum well. The light modulation layer 103 includes a buffer layer 218, a lower contact layer 210, a refractive index modulation layer 230, and an upper contact layer 213. The buffer layer 218 is made of the same semiconductor material as that of the buffer layer 201 or the intermediate layer 203, and has a function of alleviating a decrease in crystal quality due to accumulated strain accompanying the stacking of the light absorption layers.

The lower contact layer 210 is made of a semiconductor doped with an n-type dopant, and is located above the buffer layer 218 in the drawing.
The refractive index modulation layer 230 includes an intermediate layer 211 and a quantum well layer 212. The intermediate layer 211 is made of an i-type semiconductor and is located above the lower contact layer 210 in the drawing. The quantum well layer 212 is located above the lowermost intermediate layer 211 in the drawing. The next intermediate layer 211 is located above the quantum well layer 212.

  The refractive index modulation layer 230 preferably further includes a repetition of layers having the quantum well layer 212 and the intermediate layer 211 in the above order. By repeatedly arranging such layers, the wavelength band of light can be efficiently modulated. The number of layers of the refractive index modulation layer 230 can be adjusted by the wavelength, material, thickness, device size, and voltage. For example, about 10 to 100 repetitions of such a layer can be included.

The upper contact layer 213 is made of a semiconductor doped with an n-type dopant, and is located above the uppermost intermediate layer 211 in the drawing.
As described above, since the light modulation layer 103 includes the plurality of quantum well layers 212, it is possible to efficiently modulate the wavelength band necessary for selecting light having a desired wavelength.

  In the present embodiment, the lower contact layer 210 is in contact with the lower electrode 214 on the upper surface in the drawing. In the portion where the lower contact layer 210 and the lower electrode 214 are in contact, the intermediate layer 211 or the quantum well layer 212 is not in contact with the upper surface of the lower contact layer 210.

  In the present embodiment, the upper contact layer 213 is in contact with the upper electrode 215 on the upper surface in the drawing. In the portion where the upper contact layer 213 and the upper electrode 215 are in contact, the second reflective film 105 is not in contact with the upper surface of the upper contact layer 213.

  The voltage source 216 can be connected to the upper electrode 215 and the lower electrode 214. By connecting the voltage source 216 to each electrode, a desired voltage is applied between the lower contact layer 210 and the upper contact layer 213.

When the voltage source 216 applies a voltage to the light modulation layer 103, the light modulation layer 103 changes the effective refractive index of the quantum well layer with respect to the incident infrared rays 107. Thereby, since the refractive index applied to the entire layer inside the resonator 106 changes, it is possible to modulate the wavelength band necessary for selecting light of a desired wavelength.
In the present embodiment, the second reflective film 105 is located above the upper contact layer 213 in the drawing.

  The first reflection film 104 and the second reflection film 105 are made of a distributed reflection multilayer film, a dielectric multilayer film, or a metal thin film by stacking semiconductors. By comprising such a film, the first reflective film 104 and the second reflective film 105 have a specific reflectance with respect to the infrared rays 107.

  Here, the specific reflectance is preferably greater than 0% and less than 100% in the first reflective film 104. In the second reflective film 105, the specific reflectance is preferably greater than 0% and not greater than 100%. The specific reflectivity determines the finesse (Q value) of the resonator 106.

  By comprising such a film, it is possible to select the first reflective film 104 and the second reflective film 105 having desired transmission / reflectance. Since the first reflective film 104 and the second reflective film 105 have such transmittance and reflectance, the resonator 106 can satisfy one of the conditions for efficiently generating a standing wave.

  Further, the reflectance of the two reflecting films and the wavelength of infrared light determine the ratio of the height and width of each peak shown in FIG. Therefore, by selecting the respective reflectances of the first reflective film 104 and the second reflective film 105, a desired peak height to width ratio can be obtained.

By appropriately selecting the material of the first reflective film 104 from the above materials, the first reflective film 104 can transmit the infrared rays 107 incident from below in the figure with almost no reflection. As a material of the first reflective film 104, a material having a low absorptance at an infrared wavelength to be detected such as SiO _{2 or} GaAs is preferable. The infrared rays 107 that have passed through the first reflective film 104 are incident on the photoelectric converter 100.

  By appropriately selecting the material of the second reflective film 105 from the above-mentioned materials to be a metal film, the second reflective film 105 includes most of the infrared rays 107 incident from below in the figure including light of a specific wavelength. Reflects light. When the reflective film 105 is a distributed reflective multilayer film, only light of a specific wavelength (near) is efficiently reflected and other light is transmitted.

  However, since a standing wave stands in the space between the two reflecting films according to the distance between the first reflecting film 104 and the second reflecting film 105 and the refractive index between the reflecting films, it accumulates in time. The resonance wavelength is limited. For this reason, the photoelectric conversion layer 220 can detect only light of a specific wavelength.

The distance between the first reflective film 104 and the second reflective film 105, that is, the length of the resonator 106 is larger than the wavelength of the infrared light 107. The photoelectric converter 100 has a discrete resonance wavelength band having a plurality of peaks or maximum wavelengths. The spectrum of the maximum wavelength and the resonance wavelength band is determined according to the length of the resonator and the refractive index applied to the entire layer inside the resonator 106.
The refractive index of the light modulation layer 103 changes with voltage application. For this reason, since the refractive index concerning the whole layer inside the resonator 106 changes, the resonance wavelength band of the resonator 106 changes.

Each component of the photoelectric converter 100 is selected so as to satisfy the following conditions according to the above.
The resonance wavelength band of the resonator 106 overlaps or coincides with the absorption wavelength band of the light absorption layer 102 at a specific wavelength of light in the infrared light 107. Alternatively, the resonance wavelength band and the maximum wavelength of the absorption wavelength band overlap. Alternatively, the maximum wavelength of the resonance wavelength band and the absorption wavelength band overlap. Alternatively, the maximum wavelength in the resonance wavelength band coincides with the maximum wavelength in the absorption wavelength band.
As described above, when the resonance wavelength band and the absorption wavelength band match or overlap each other, the infrared detector 200 selectively detects only infrared rays having a specific wavelength.

2. Principle of Operation The operation of the infrared detector 200 will be described with reference to FIGS. 3A to 5. 3A and 3B are schematic views for explaining the principle of light absorption or photoelectric conversion of the light absorption layer 102 according to the first embodiment. This schematic diagram shows an electron energy band structure in a region from one intermediate layer 203 to the adjacent intermediate layer 203.

  As described above, the photoelectric conversion layer 220 has the repetition of layers in the order of the intermediate layer 203, the quantum dot layer 204, the strain relaxation layer 217, and the next intermediate layer 203 from the lower side in the drawing. The direction from left to right in FIGS. 3A and 3B corresponds to the direction from top to bottom in FIG. The left side of FIGS. 3A and 3B represents the lower contact layer 202 side.

3A and 3B, based on quantum mechanics, the electrons bound by the quantum dot layer 204 and the strain relaxation layer 217 can take only discrete energy levels. In Figure 3A, of the discrete energy levels, it represents a ground state ₃₀₁₁ an excited state 302 _1.
Infrared light 304 having the same photon energy to the ground state 301 ₁ an excited state 302 ₁ of the energy difference (first energy difference). Electronic 300 when infrared light 304 electron 300 of the ground state 301 ₁ absorbs the transition to an excited state 302 _1.

The voltage source 208 applies a negative bias voltage. Therefore, it is possible to detect the electrons 300 in which the transition to the excited state 302 ₁ photocurrent. The infrared detector 200 including the ammeter 209 operates as a detector. Light absorption occurs because the first quantum dots having an energy difference matching the photon energy of the infrared light 304 are present in the light absorption layer 102. Without such quantum dots, light absorption does not occur efficiently, so the sensitivity of the infrared detector 200 is almost zero.

In Figure 3B, of the discrete energy levels, and it represents the ground state 301 ₂ an excited state 302 _2. Explanation of elements having the same reference numerals as those in FIG. 3A is omitted. Long infrared light 305 having a wavelength from infrared light 304 having the same photon energy to the ground state 301 ₂ an excited state ₃₀₂₂ of the energy difference (second energy difference).

Electronic 300 when infrared light 305 electrons 300 in the ground state 301 ₂ absorbs the transition to the excited state 302 _2. Electrons 300 in which the transition to the excited state 302 ₂ can be detected as a photocurrent. Light absorption occurs because the second quantum dots having an energy difference matching the photon energy of the infrared light 305 are present in the light absorption layer 102.

  As described above, in the photoelectric converter 100, the first energy difference between the energy levels of electrons bound to the first quantum dots matches the photon energy of light in the first resonance wavelength band of the optical resonator. Yes. In addition, the second energy difference between the energy levels of the electrons bound to the second quantum dots matches the photon energy of light in the second resonance wavelength band of the optical resonator.

  As described above, the modulation unit modulates the resonance wavelength band from the first resonance wavelength band to the second resonance wavelength band. Similarly, the resonance wavelength band is modulated from the second resonance wavelength band to the first resonance wavelength band. For this reason, the infrared detector 200 including the photoelectric converter 100 can selectively detect the light intensity in a plurality of wavelength bands.

The ground states 301 ₁ and 301 ₂ and the excited states 302 ₁ and 302 ₂ can be controlled by the size, shape, and material of the quantum dots in the quantum dot layer 204. For this reason, they can be selected such that the quantum dots have a desired energy difference. That is, infrared light 304 having a wavelength in a desired wavelength band can be selected as a detection target.

As described above, since the plurality of quantum dots have different energy differences, as shown in FIG. 4B, as the first absorption wavelength band 400 and the second absorption wavelength band 401 of the light absorption layer 102, desired An absorption wavelength peak having a maximum wavelength can be selected. For this reason, the light absorption layer 102 has a discrete absorption wavelength band.
The first absorption wavelength band 400 corresponds to the first energy difference described above. The second absorption wavelength band 401 corresponds to the above-described second energy difference.

  FIG. 4 shows (A) the resonance spectrum of the resonator 106, (B) the absorption spectrum of the light absorption layer 102, and (C) the detection spectrum of the infrared detector 200. FIG. 5 shows (A) the resonance wavelength band or characteristics of the resonator 106, (B) the absorption wavelength band or characteristics of the light absorption layer 102, and (C) the detection wavelength band or sensitivity of the infrared detector 200.

As shown in FIG. 4A, the infrared light 304 exists as a standing wave in the resonator 106 together with light in other specific wavelength bands. As shown in FIGS. 1 and 2A, only light having a specific wavelength in the spectrum of incident infrared light 107 exists as a standing wave inside the resonator 106. As an example of such light, infrared light 304 having a wavelength λ ₁ and a peripheral wavelength band exists as a standing wave inside the resonator 106.

  As described above, when the infrared rays 107 are incident through the first reflecting film from below in the drawing, the resonators 106 formed by the first reflecting film 104 and the second reflecting film 105 cause the infrared light 304 and other specificities. This is because only light in this wavelength band resonates.

As shown in FIG. 4B, the light absorption layer 102 has a first absorption wavelength band 400 or a second absorption wavelength band 401 that can be absorbed. When light having a wavelength λ ₁ applied to the first absorption wavelength band 400 or light having a wavelength λ ₂ applied to the second absorption wavelength band 401 is incident, the light is absorbed and a photocurrent is generated. In such a case, the voltage source 208 needs to apply a negative bias voltage to the light absorption layer 102.

It is preferable that the wavelength interval between the first absorption wavelength band 400 and the second absorption wavelength band 401 does not coincide with the free spectral range (FSR) of the resonance wavelength characteristic of the resonator 106.
The voltage source 216 applies a bias voltage to the light modulation layer 103. Depending on the magnitude of the applied voltage, the wavelength of the standing wave existing inside the resonator 106 changes, and the resonance wavelength characteristic changes.

The refractive index of the light modulation layer 103 is modulated by, for example, the quantum well quantum confined stark effect (QCSE) of the quantum well. Under an appropriate applied voltage, the first absorption wavelength band 400 and one of the resonance wavelengths of the resonator overlap or match. One of the resonance wavelengths is the wavelength band or wavelength of the infrared light 304.
Of the light that exists as a standing wave within the resonator, the absorption happens is only infrared light 304, the photoelectric converter 100 has a sensitivity only to the wavelength lambda ₁ in the conditions.

  At this time, the structure of each semiconductor layer and the light absorption layer 102 in the resonator 106 can be selected so that the photoelectric converter 100 has the first absorption wavelength band 400 in a state where no voltage is applied to the light modulation layer 103.

Next, by applying an appropriate voltage to the light modulation layer 103, the resonance wavelength characteristic of the resonator 106 can be modulated as shown in FIGS. 4A to 5A. The resonance wavelength characteristic of the resonator can be selected so that only the same wavelength as the wavelength λ ₂ matches the second absorption wavelength band 401 of the light absorption layer 102 among the maximum wavelengths of the resonance wavelength band. After resonant wavelength by the modulation of the light modulating layer 103 has Δλ changed, infrared detector 200 has no sensitivity at a wavelength of lambda _1, having sensitivity only to the wavelength lambda _2.

  That is, since the photoelectric converter 100 includes the light absorption layer 102 and the modulation unit described above, the photoelectric converter 100 has the following characteristics. In the photoelectric converter 100, the maximum wavelength of the first resonance wavelength band overlaps with the first absorption wavelength band 400 and does not overlap with the second absorption wavelength band 401. On the other hand, in the photoelectric converter 100, the maximum wavelength of the second resonance wavelength band does not overlap with the first absorption wavelength band 400 and overlaps with the second absorption wavelength band 401. With this configuration, only a specific wavelength can be detected efficiently.

  Further, the resonance wavelength band may be further modulated from the second resonance wavelength band to the first resonance wavelength band by modulation of the resonator 106. With this configuration, an appropriate detection wavelength can be selected in a timely manner. The above voltage application is an example of a method for changing the refractive index of the light modulation layer 103 and the resonance wavelength characteristic of the resonator 106.

  Further, since the light absorption characteristics of the light absorption layer 102 change on the wavelength axis, the same wavelength selection operation can be performed without depending on the resonance wavelength of the resonator. FIG. 6 shows measurement results of sensitivity for each wavelength when a positive bias and a negative bias are applied to a representative quantum dot layer 204. That is, FIG. 6 illustrates the modulation method on the light absorption layer 102 side.

  The data in FIG. 6 is actually measured data of a change in sensitivity spectrum or absorption spectrum when a positive bias (solid line 501) and a negative bias (dashed line 500) are applied to a QDIP composed of uniform-sized quantum dots.

  For this reason, when the light absorbing layer having the characteristics shown in FIG. 6 is laminated by adding strain relaxation layers having different thicknesses or dots having different sizes, the discrete layers as shown in FIG. 4 and FIG. Spectrum is obtained.

Since the infrared detector according to the present embodiment has the above-described configuration, it is possible to select and detect only a specific wavelength from light having a wavelength that can be absorbed by the light absorption layer.
The light detection method of this embodiment will be described with reference to FIGS. The light detection method of the present embodiment is a method of detecting light in the infrared light 107 using the infrared detector 200 in the following steps.

  In the modulation step, the voltage source 216 modulates the resonance wavelength band of the resonator 106 by generating or changing the voltage applied to the modulation means. Specifically, a voltage is applied to the modulation means through an input unit including an upper electrode 215 and a lower electrode 214. When a voltage is applied to the light modulation layer 103 in the modulation means, the refractive index is modulated in the refractive index modulation layer 230.

  Before the modulation, the maximum wavelength (corresponding to infrared light 304) in the first resonance wavelength band overlaps with the first absorption wavelength band 400 in the absorption wavelength band of the light absorption layer 102. After modulation, the maximum wavelength (corresponding to infrared light 305) in the second resonance wavelength band overlaps with the second absorption wavelength band 401. Since the light absorption layer 102 has a quantum confinement structure, it has a discrete absorption wavelength band. For this reason, the photoelectric converter 100 can selectively change the absorption wavelength band by performing the above-described modulation.

In the light receiving step, the photoelectric converter 100 receives light contained in the infrared rays 107. Specifically, the photoelectric converter 100 receives light from a direction perpendicular to a plane parallel to the light absorption layer 102.
In the optical resonance process, light is resonated in the resonator 106. Specifically, light is repeatedly reflected in the optical path between the first reflective film 104 and the second reflective film 105 whose refractive index is modulated by the light modulation layer 103. Thereby, only the light in the resonance wavelength band resonates.

  In the light absorption process, the quantum confinement structure of the light absorption layer 102 absorbs the resonated light. Specifically, the light in the second absorption wavelength band 401, that is, the infrared light 305 is absorbed. The absorption wavelength band becomes a second absorption wavelength band 401 due to modulation, and overlaps with the infrared light 305. For this reason, since the number of photons is increased by resonance, light of a specific wavelength can be selectively absorbed.

  Further, light within the first absorption wavelength band 400, that is, infrared light 304 is hardly absorbed. The absorption wavelength band becomes a second absorption wavelength band 401 due to modulation, and hardly overlaps with the infrared light 304. For this reason, since the number of photons is not increased, light of other wavelengths can be selectively not absorbed.

  In the photoelectric conversion step, the absorbed light is photoelectrically converted by the light absorption layer 102, and a voltage is applied by the detection voltage source to generate a current. In the detection step, the ammeter detects current. For this reason, light of a specific wavelength can be selectively detected as a current.

  The light detection method can also be configured as follows. In the first measurement step, light in the first absorption wavelength band 400 is detected without applying a voltage to the modulation means, and the light intensity is measured. Next, in the second measurement step, a voltage is applied to the modulation means through the voltage source 216, the light in the second absorption wavelength band 401 is detected, and the light intensity is measured.

  Other light detection methods can also be configured as follows. In the first measurement step, the first voltage is applied to the modulation means through the voltage source 216, the light in the first absorption wavelength band 400 is detected, and the light intensity is measured. Next, in the second measurement step, a second voltage is applied to the modulation means through the voltage source 216, the light in the second absorption wavelength band 401 is detected, and the light intensity is measured.

  In the method of the present embodiment, even when the wavelength detected by the infrared detector is greatly changed, the external force necessary for this is sufficient with a small force necessary for changing the resonance wavelength characteristic. For this reason, it is possible to change a detection wavelength with little power consumption.

  As described above, by modulating the refractive index by voltage application from a voltage source, it is possible to select and detect only a specific wavelength at an appropriate timing during the detection operation of the infrared detector 200.

  In this embodiment, the infrared detector can selectively detect a plurality of wavelengths of 2 or more by appropriately selecting quantum dots in the quantum dot layer. For this reason, even if the photoelectric converter or infrared detector of this embodiment is a simple structure provided with only one light absorption layer, a plurality of spectra can be detected.

3. Manufacturing Next, a manufacturing method of the photoelectric converter 100 and the infrared detector 200 according to the present embodiment will be described with reference to FIG.

(1) Method of Forming Light Absorbing Layer 102 by Crystal Growth As a semiconductor substrate 101, a GaAs substrate having a (001) plane orientation is prepared. A semiconductor substrate 101 having a desired thickness can be obtained by substrate polishing or the like. A desired resonance wavelength can be obtained by appropriately selecting the thickness of the semiconductor substrate 101.

  This substrate is introduced into a molecular beam epitaxial apparatus and irradiated with an As molecular beam obtained by heating and sublimating solid As. During irradiation, the substrate temperature is raised to 600 ° C., and the natural oxide film on the surface of the semiconductor substrate 101 is removed.

Next, after the substrate temperature is set to about 580 ° C., a buffer layer 201 having a thickness of 500 nm and made of the same GaAs as the semiconductor substrate 101 is laminated. Subsequently, an n-type lower contact layer 202 made of GaAs having a thickness of 500 nm is stacked. GaAs is previously doped with Si atoms at a concentration of about 2 × 10 ¹⁸ cm ⁻³ . Further, an i-type intermediate layer 203 made of GaAs having a thickness of 50 nm is stacked.

  Next, after the substrate temperature is set to about 490 ° C., an amount of InAs is supplied to the surface of the intermediate layer 203 so as to have a thickness of about 2 to 3 atomic layers if it uniformly spreads on the surface of the intermediate layer 203. . At this time, InAs grows into a three-dimensional island shape due to the strain generated from the difference in lattice constant between InAs and GaAs, and forms SK mode quantum dots.

As a result, in the quantum dot layer 204, the quantum dots are arranged in a plane on the surface of the intermediate layer 203. In the quantum dot layer 204, a typical quantum dot has a diameter of 30 nm and a height of 5 nm, and the number density of quantum dots per square centimeter of the quantum dot layer 204 is about 5 × 10 ¹⁰ .

  In this embodiment, two types of quantum dots may be used in order to have discrete absorption wavelength characteristics. The size of the quantum dots can be adjusted by the amount of InAs, the substrate temperature, and the growth time during the above-described quantum dot formation. The shape of the quantum dots can also be adjusted by the amount of InAs, the substrate temperature, the growth time, and the material of the substrate and intermediate layer.

  Subsequently, Si atoms that are n-type dopants are supplied directly above the quantum dot layer 204. The number density of Si atoms is set to the same level as the number density of the quantum dots. Next, the supply of InAs is stopped.

  Si atoms function as dopants and supply electrons to the quantum dots. For this reason, Si atoms improve the sensitivity of the photodetector. Since Si atoms do not have a strong influence on the wavelength characteristics and the like, they may be supplied in the form of being sprinkled on the quantum dot layer 204 (not shown). It is preferable to sprinkle the same number of Si atoms as the quantum dots.

  Si atoms may reach not only the quantum dots in the quantum dot layer 204 but also the intermediate layer 203. Note that InAs is supplied onto the intermediate layer 203 when quantum dots are formed. For this reason, the intermediate layer 203 is rarely exposed in the portion where the quantum dots are not formed. On the other hand, a thin InAs film, that is, a so-called wetting layer is formed in a portion where no quantum dot is formed.

  Next, a strain relaxation layer 217 made of InGaAs having a thickness of about 5 to 10 nm is stacked on the quantum dot layer 204. After the temperature is set to 580 ° C., an i-type intermediate layer 203 made of GaAs having a thickness of 50 nm is laminated.

  In this embodiment, in order to have discrete absorption wavelength characteristics, the quantum dot layer 204 may be made of the same quantum dots, and the thickness of the strain relaxation layer 217 may be different. For example, the thickness of the strain relaxation layer 217 may be 5 nm or 10 nm for each different layer. In such a case, the quantum dots of each quantum dot layer 204 stacked on the strain relaxation layer 217 having the respective thicknesses have different absorption wavelength characteristics between the quantum dot layers 204.

The photoelectric conversion layer 220 including quantum dots is formed by repeating the stacking of the quantum dot layer 204, the strain relaxation layer 217, and the intermediate layer 203 about 10 to 20 times according to the above procedure. On the photoelectric conversion layer 220, an n-type upper contact layer 205 having a thickness of 200 nm and containing GaAs doped with Si atoms at a concentration of about 2 × 10 ¹⁸ cm ⁻³ is laminated.

  When forming the quantum dot layer 204, a material other than InAs, such as InGaAs, InSb, GaN, or GaSb, may be used as long as the material has a lattice constant different from that of the intermediate layer 203.

  When the strain relaxation layer 217 is formed, a material other than InGaAs such as AlGaAs, GaAs, InSb, InGaSb may be used. When forming the semiconductor substrate 101, a substrate made of InP, Ge, Si, or the like other than the GaAs substrate may be used. In the above description, the MBE method is used when forming the quantum dots and the peripheral structure, but other methods such as a metal organic chemical vapor deposition (MOCVD) method may be used.

(2) Method for Forming Light Modulation Layer 103 A buffer layer 218 is stacked immediately above the upper contact layer 205 of the light absorption layer 102. The lower contact layer 210 and then the intermediate layer 211 are laminated under the same conditions as in the light absorption layer. Further, a quantum well layer 212 made of, for example, InGaAs is stacked. The refractive index modulation layer 230 is formed by repeating the stacking of the intermediate layer 211 and the quantum well layer 212 in the same procedure as described above. Thereafter, an n-type upper contact layer 213 is stacked on the uppermost intermediate layer 211.

  In order to perform efficient refractive index modulation, it is desirable to repeat the stacking of the quantum well layer 212 and the intermediate layer 211 a plurality of times. In order to obtain a desired resonance wavelength, the thickness of the intermediate layer 211 and the buffer layer 218 can be appropriately selected.

(3) Production of Reflective Film The first reflective film 104 is formed by laminating a metal thin film or a dielectric multilayer film on the lower surface of the semiconductor substrate 101 in the drawing. Further, a second reflective film 105 is formed by laminating a metal thin film or a dielectric multilayer film on the upper surface of the upper contact layer 213 in the drawing.

  As shown in FIGS. 1 and 2A, when the infrared rays 107 are incident from below in the drawing, the second reflection film 105 can be formed by laminating a metal film that causes complete reflection with respect to the detection wavelength. In addition, the incident direction of the infrared rays 107 is not limited to the lower part in the figure as in FIGS. 1 and 2A. For this reason, although not shown in the drawing, the infrared rays 107 may be incident on the upper side in the drawing, that is, from the second reflective film 105 side. In this case, the first reflective film 104 can be formed by laminating a metal film that causes complete reflection with respect to the detection wavelength.

  The first reflective film 104 and the second reflective film 105 may be formed as a distributed Bragg reflector (DBR). Although not shown in the drawing, it is preferable to form the first reflective film 104 by stacking semiconductors having different refractive indexes between the semiconductor substrate 101 and the buffer layer 201. Further, it is preferable to form a second reflective film 105 by stacking a semiconductor having a refractive index different from that of the upper contact layer 213 in the drawing.

(4) Detector structure processing and electrode process Subsequently, the second reflective film 105, the light modulation layer 103, and a part of the light absorption layer 102 are selectively etched by ultraviolet lithography and dry etching. As a result, the upper contact layer 205 and the upper contact layer 213, and a part of the upper surface of the lower contact layer 202 and the lower contact layer 210 in the drawing are exposed. Thus, the structure independent of the surroundings by selective etching corresponds to the photoelectric converter 100 that is one element of the infrared detector 200.

The infrared detector 200 may be composed of only one element, or may be an array in which such elements are arranged in one row or two-dimensionally.
Subsequently, an upper electrode 215 and an upper electrode 207 made of AuGe / Ni / Au, and a lower electrode 214 and a lower electrode 206 are formed on each upper contact layer and each lower contact layer. Each electrode is preferably formed by a lift-off method including processes such as lithography, metal deposition, and resist stripping.

[Second Embodiment]
In the following description of the second to fourth embodiments, the same components as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. FIG. 7 shows a photoelectric converter 600 of this embodiment. The photoelectric converter 600 includes a semiconductor substrate 601, a light absorption layer 602, a light modulation layer 603, a first resonator 606 (first optical resonator), a second resonator 607 (second optical resonator), and a light transmission layer. 613.

  The light absorption layer 602 has a photoelectric conversion function. The light absorption layer 602 includes a buffer layer 201, a lower contact layer 202, a photoelectric conversion layer 220, and an upper contact layer 205. The light modulation layer 603 includes a buffer layer 218, a lower contact layer 210, a refractive index modulation layer 230, and an upper contact layer 213.

  The first resonator 606 is a first optical resonator serving as a main resonator. The first resonator 606 includes a first reflecting part 617 and a second reflecting film 605 in the first reflecting film 604. The second resonator 607 is a second optical resonator serving as a sub resonator. The second resonator 607 includes a third reflective film 614 and a second reflective part 615 in the first reflective film 604. The photoelectric converter 600 may further include a lower electrode 206 and an upper electrode 207.

  The lower electrode 214 and the upper electrode 215 receive an applied voltage from a voltage source as an input to the light modulation layer 603. The lower electrode 214, the upper electrode 215, and the light modulation layer 603, as modulation means, modulate the resonance wavelength band of the resonator 106 in accordance with the generation or change of the applied voltage.

  As an overview, the photoelectric converter 600 includes all the components of the photoelectric converter 100, and further includes the second resonator 607 and the light transmission layer 613. The photoelectric converter 600 is connected to a voltage source 208, an ammeter 209, and a voltage source 216 (not shown). The second resonator 607 has different FSR and resonance wavelength characteristics from the first resonator 606.

  The operation principle of the photoelectric converter 600 will be described with reference to FIGS. 8A to 9E. 8A shows the resonance wavelength characteristic of the first resonator 606, and FIG. 8B shows the resonance wavelength characteristic of the second resonator 607, respectively. The first resonator 606 and the second resonator 607 constitute one composite resonator system.

  In the composite resonator system, only the resonance wavelength band (composite resonance wavelength band) that exists in common in both of the resonance wavelength bands of the first resonator 606 and the second resonator 607 exists as a standing wave. . For this reason, the photoelectric converter 600 including the composite resonator system has a resonance wavelength characteristic as shown in FIG. 8C.

As shown in FIG. 8D, the light absorption layer 602 has an absorption wavelength band including a wavelength λ ₁ that overlaps or coincides with the resonance wavelength band of FIG. 8C, that is, a first absorption wavelength band 700. As the standing wave is absorbed, the photoelectric converter 600 is sensitive to the resonance wavelength applied to the composite resonator system. That is, as shown in FIG. 8E, the photoelectric converter 600 is sensitive only to infrared rays in the first absorption wavelength band 700, which is one of the absorption wavelength bands of the light absorption layer 602.

  Before the modulation by the modulating means, it is preferable that the first energy difference between the energy levels of the electrons bound to the first quantum dots and the photon energy of the light in the first composite resonance wavelength band coincide. The energy difference is particularly preferably coincident with the photon energy of the light having the maximum wavelength in the composite resonance wavelength band. With this configuration, only a specific wavelength can be detected efficiently.

  A modulation voltage source (not shown) applies an external force such as generation or change of an applied voltage to the light modulation layer 603 to change the refractive index of the refractive index modulation layer 230. For this reason, as shown in FIG. 9A, the resonance wavelength characteristic in the first resonator 606 changes. The resonance wavelength characteristic of the first resonator 606 changes from a broken line to a solid line. By such modulation, the composite resonance wavelength band is modulated from the first composite resonance wavelength band to the second composite resonance wavelength band.

On the other hand, as shown in FIG. 9B, the resonance wavelength characteristic of the second resonator 607 is not changed from that of FIG. 8B. FIG. 9C shows the resonance wavelength characteristics of the composite resonator system at this time. The resonance wavelength band at this time overlaps or coincides with the second absorption wavelength band 701 of the light absorption layer 602 shown in FIG. 9D. For this reason, as shown in FIG. 9E, the photoelectric converter 600 has sensitivity only in this wavelength band. The second absorption wavelength band 701 is a wavelength band including the wavelength lambda _2.

  After the modulation by the modulation means, it is preferable that the second energy difference between the energy levels of the electrons bound to the second quantum dots coincides with the photon energy of the light in the second composite resonance wavelength band. The energy difference is particularly preferably coincident with the photon energy of the light having the maximum wavelength in the composite resonance wavelength band. With this configuration, only a specific wavelength can be detected efficiently.

It is preferable that the maximum wavelength of the first composite resonance wavelength band overlaps with the first absorption wavelength band 700 and does not overlap with the second absorption wavelength band 701. In addition, it is preferable that the maximum wavelength of the second composite resonance wavelength band does not overlap with the first absorption wavelength band 700 and overlaps with the second absorption wavelength band 701. With this configuration, only a specific wavelength can be detected efficiently.
Further, by the modulation of the first resonator 606, the composite resonance wavelength band may be further modulated from the second composite resonance wavelength band to the first composite resonance wavelength band. With this configuration, an appropriate detection wavelength can be selected in a timely manner.

In the above, the refractive index of the light modulation layer 603 inside the first resonator 606 is changed in order to change the resonance wavelength characteristic. On the other hand, the second resonator 607 may be modulated by acting on the light transmission layer 613. Alternatively, the resonance wavelength characteristics of both the first resonator 606 and the second resonator 607 may be modulated.
As shown in FIGS. 9A to 9E, the photoelectric converter 600 of the present embodiment can change the detection wavelength greatly by minute refractive index modulation.

  Further, the absorption wavelength band, that is, the absorption spectrum may be widened due to the non-uniform width of the light absorption layer 602. The non-uniform width of the light absorption layer 602 is a broadening of the absorption spectrum due to variations in process and quality of the light absorption layer 602. Specifically, it is a quantum dot and a strain relaxation layer in the light absorption layer 602. In the present embodiment, the non-uniform width of the light absorption layer 602 is preferably the full width at half maximum of the absorption spectrum.

  Here, the line width of the detection sensitivity of the photoelectric converter 600 can be limited by the first resonator 606 or the second resonator 607. For this reason, in the photoelectric converter 600 of this embodiment, compared with the photoelectric converter 100 of 1st Embodiment, there exists an effect which can raise the wavelength detection precision of an infrared detector provided with this.

[Third Embodiment]
A photoelectric converter 800 according to the third embodiment shown in FIG. 10 is obtained by replacing the light modulation layer 103 and the resonator 106 included in the photoelectric converter 100 according to the first embodiment with a resonator type filter 806. is there.

  The semiconductor substrate 101 and the light absorption layer 102 are located outside the resonator type filter 806. The resonator type filter 806 is an optical resonator, and at the same time, modulation means. The resonator type filter 806 modulates the resonance wavelength band of the resonator type filter 806 itself according to the generation or change of the applied voltage.

The resonator type filter 806 includes a first reflective film 804, a second reflective film 805, a lower electrode 814, and an upper electrode 815. The first reflective film 804 is in contact with the lower electrode 814 on the lower surface in the drawing. The second reflective film 805 is in contact with the upper electrode 815 on the upper surface in the drawing. The lower electrode 814 and the upper electrode 815 receive an applied voltage from a voltage source as an input to the resonator type filter 806.
The voltage source 816 can be connected to the upper electrode 815 and the lower electrode 814. By connecting the voltage source 816 to each electrode, a desired voltage is applied between the first reflective film 804 and the second reflective film 805.

  When the voltage source 816 applies a voltage to the resonator type filter 806, the resonance wavelength characteristic of the resonator type filter 806 changes. This change is equivalent to the change from FIG. 4B to FIG. 5B according to the first embodiment. For this reason, the photoelectric converter 800 can select a wavelength band similarly to the photoelectric converters of the first and second embodiments.

  As the resonator type filter 806, an etalon filter, a liquid crystal, or a resonator type filter including a MEMS (Micro Electro Mechanical System) can be selected.

The light absorption layer 102 preferably includes an antireflection film on the resonator type filter 806 side. Specifically, the light absorption layer 102 can include an antireflection film on the upper surface in the drawing of the upper contact layer 205 at the top. The antireflection film is preferably made of a dielectric thin film such as TiO ₂ or SiO ₂ . With such an antireflection film, reflection of infrared rays on the surface of the light absorption layer 102 can be suppressed.
In the present embodiment, the light absorption layer and the optical resonator can be combined as separate components. For this reason, the infrared detector provided with the photoelectric converter 800 corresponds to various detection wavelengths.

[Fourth Embodiment]
A photoelectric converter 900 according to the fourth embodiment shown in FIG. 11 is obtained by replacing the resonator 106 in the photoelectric converter 100 of the first embodiment with a resonator 906. The photoelectric converter 900 includes a semiconductor substrate 101, a light absorption layer 102, a driving unit 903, a resonator 906, an electrode 914, and an electrode 915.

  The resonator 906 is an optical resonator. The resonator 906 includes a first reflecting mirror 904 and a second reflecting mirror 905. The electrodes 914 and 915 receive an applied voltage from a voltage source as an input unit to the driving unit 903. The drive unit 903, the electrode 914, and the electrode 915 modulate the resonance wavelength band of the resonator 906 according to the generation or change of the applied voltage as modulation means.

  The first reflecting mirror 904 is located below the semiconductor substrate 101 in the drawing. The semiconductor substrate 101, the light absorption layer 102, and the first reflecting mirror 904 collectively constitute one element. The second reflecting mirror 905 is provided in the photoelectric converter 900 apart from such an element. In the present embodiment, the light absorption layer 102 is located above the drawing.

  When the drive unit 903 moves the second reflecting mirror 905 in the vertical direction in the figure, the distance between the reflecting mirrors changes. For this reason, the resonance characteristics of the resonator 906 change, and the photoelectric converter 900 can select a wavelength to be detected.

The 2nd reflective mirror 905, the drive part 903, the electrode 914, and the electrode 915 can be comprised as a drive mirror provided with MEMS etc., for example. On the other hand, the 1st reflective mirror 904, the semiconductor substrate 101, and the light absorption layer 102 can be comprised as an element for photoelectric converters.
The distance between the first reflecting mirror 904 and the second reflecting mirror 905 is changed by applying a voltage to the driving unit 903 that moves the second reflecting mirror 905. For this reason, the resonance wavelength characteristic of the resonator 906 changes.

As a modification of the present embodiment, the photoelectric converter 900 can include a first reflecting mirror 904 that is independent from the one element. Further, the second reflecting mirror 905 can be positioned above the light absorption layer 102 in the drawing. In this case, the semiconductor substrate 101, the light absorption layer 102, and the second reflecting mirror 905 collectively constitute one element.
The photoelectric converter 900 can be combined as a separate component from the light absorption layer and the optical resonator. For this reason, an infrared detector provided with the photoelectric converter 900 can cope with various detection wavelengths.

[Description of effects]
The QDIP disclosed in Non-Patent Document 1 has sensitivity to three wavelengths, but cannot distinguish signals for each wavelength and can extract only as a sum of signals in three wavelength bands. In order to independently extract signals of each wavelength, an independent narrow band wavelength filter is required for each element, which causes a complicated structure of the apparatus.

  On the other hand, QDIP disclosed in Patent Document 1 has two or more light absorption layers in order to detect light having a plurality of wavelengths. For this reason, a manufacturing process becomes complicated and production efficiency is low. Also, since polarized light is used, a polarizing filter is necessary. In the present embodiment, the polarizing filter is a filter that transmits only specific polarized light, that is, a polarizer.

  On the other hand, the narrow band wavelength filter is unnecessary in the photoelectric converters of the above embodiments. Further, a single light absorption layer can detect light having a plurality of wavelengths. For this reason, since a manufacturing process can be simplified, production efficiency is high.

  The infrared detector according to each of the embodiments includes a light absorption layer having one or more discrete absorption wavelengths and an optical resonator having one or more discrete resonance wavelengths. The infrared detector of this embodiment modulates at least one of the absorption wavelength of the light absorption layer or the resonance wavelength of the optical resonator with an external force.

  Due to such an external force, one of the absorption wavelengths of the light absorption layer coincides with one of the resonance wavelengths of the optical resonator. For this reason, the infrared detector of this embodiment can select and detect any one of one or more discrete absorption wavelength peaks of the light absorption layer.

  The wavelength selection method of each of the above embodiments includes a step of modulating at least one of one or more discrete absorption wavelengths or one or more discrete resonance wavelengths with an external force. Due to such an external force, one of the absorption wavelengths of the light absorption layer coincides with one of the resonance wavelengths of the optical resonator. In the wavelength selection method according to the present embodiment, any one of one or more discrete absorption wavelength peaks of the light absorption layer can be selected and detected.

  The photodetector in each of the above embodiments is suitable as a light detector of a specific infrared detector in the mid-infrared or mid-far infrared region. The photodetector in each of the above embodiments is suitable as a light detection unit such as a heat source detection, temperature measurement, specific gas detection, or a sensor for night vision devices. In addition, the photodetector of each of the above embodiments is suitable as a light receiver for a communication device that selectively receives a specific wavelength.

[Modification of Embodiment]
The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit of the present invention. In the present embodiment, the description has focused on infrared detection technology. However, the present invention is not limited to infrared light, but can be applied to all light such as visible light and ultraviolet light.

  In each said embodiment, the light absorption layer shall have a quantum dot. As a modification of the embodiment, the light absorption layer may have a quantum confinement structure other than quantum dots. The light absorption layer may include one or more quantum confinement structures selected from the group consisting of quantum dots, quantum wires, and quantum wells. The light modulation layer according to the first and second embodiments may also include one or more quantum confinement structures selected from the group consisting of quantum dots, quantum wires, and quantum wells.

  These quantum confinement structures can be freely selected and combined. Since the light absorption layer has the quantum confinement structure, the photoelectric converter has discrete absorption wavelength characteristics. Further, since the light modulation layer has the quantum confinement structure, the photoelectric converter has discrete resonance wavelength characteristics.

  In each said embodiment, although the light absorption layer shall have the 1st and 2nd absorption wavelength band, you may have a specific absorption wavelength band further. A photoelectric converter having such a light absorption layer can be sensitive to light in three or more wavelength bands.

  The light absorption layer includes a photoelectric conversion layer having two or more quantum dots having different sizes, shapes, or materials. Alternatively, the light absorption layer includes a photoelectric conversion layer having two or more strain relaxation layers having different thicknesses or materials. For this reason, one light absorption layer produces a discrete absorption wavelength band.

  In each of the above embodiments, for example, the light absorption layer includes a first quantum dot layer having first quantum dots. The light absorption layer further includes a second dot layer having second quantum dots that are different in size, shape, or material from the first quantum dots.

  As a modification of the embodiment, one quantum dot layer may have first quantum dots and second quantum dots having different sizes, shapes, or materials. In addition, one quantum dot layer may include a first quantum dot and a second quantum dot having different sizes and shapes, sizes and materials, or shapes and materials different from each other. In addition, one quantum dot layer may have a first quantum dot and a second quantum dot that are different in size, shape, and material.

  As a variation of the embodiment, the thickness or material of the plurality of strain relaxation layers may be different. Any combination of the size, shape, and material of the quantum dots of each quantum dot layer, and the thickness and material of each strain relaxation layer located above in the drawing closest to the quantum dot layer Can be selected.

  The light absorption layer has the same number of discrete absorption wavelength peaks as the kind of combination of the quantum dot layer and the strain relaxation layer. For this reason, the light absorption layer which has said structure has many more discrete absorption wavelength peaks. Alternatively, the quantum dots may be of the same type and a discrete absorption wavelength band may be generated only by the strain relaxation layer.

  For example, the light absorption layer may include a first quantum dot, a first strain relaxation layer surrounding the first quantum dot, and a second strain relaxation layer surrounding the second quantum dot and the second quantum dot. The second strain relaxation layer is preferably different in thickness or material from the first strain relaxation layer.

  In the present embodiment, the photoelectric converter includes one light absorption layer and two contact layers sandwiching the light absorption layer. Here, the photoelectric converter may include two or more light absorption layers, and each light absorption layer may include different quantum confinement structures or strain relaxation layers.

  In this case, discrete absorption wavelength bands can be created by combining the individual absorption wavelength bands generated by the respective light absorption layers. Moreover, the thing which produces a discrete absorption wavelength band only with one light absorption layer, and the light absorption layer which produces the absorption wavelength band which has only one maximum wavelength can be combined freely.

  In the first and second embodiments, the refractive index is modulated by applying a voltage through the contact layer of the light modulation layer. As a modification of the embodiment, the refractive index can be modulated by light irradiation to the light modulation layer without using a contact layer. It is preferable that the light applied to the light irradiation is not absorbed by the light absorption layer.

  For this reason, it is preferable to select the material and structure of the light modulation layer so that the refractive index changes when irradiated with light having a wavelength other than the absorption band wavelength. Further, a light source such as a laser for light irradiation can be appropriately selected with respect to wavelength and intensity.

  The light source preferably includes a voltage input unit from a voltage source. When the voltage source applies a voltage to the light source, the light source irradiates the refractive index modulation layer with light. The light modulation layer that receives the light modulates the refractive index in the resonator. For this reason, the resonance wavelength of the optical resonator changes.

  When the voltage source stops applying a voltage to the light source, the light source stops irradiating light to the refractive index modulation layer. For this reason, the light modulation layer that has stopped receiving light modulates the refractive index in the resonator to the original state. For this reason, the resonance wavelength of the resonator is restored. The photoelectric converter includes the light source and the light modulation layer as modulation means. Such modulation means modulates the resonance wavelength band of the optical resonator in accordance with the generation or change of the applied voltage.

(Appendix 11)
The photoelectric converter according to claim 2, wherein the light in the resonance wavelength band is light having a maximum wavelength in the resonance wavelength band.

(Appendix 12)
The light absorbing layer surrounds the first quantum dots and the first strain relaxation layer that surrounds the first quantum dots, and the second quantum dots and the second quantum dots. The photoelectric converter in any one of Claims 1-3 which has a different 2nd distortion relaxation layer.

(Appendix 13)
The maximum wavelength of the first resonance wavelength band overlaps with the first absorption wavelength band, and does not overlap with the second absorption wavelength band,
6. The photoelectric converter according to claim 5, wherein a maximum wavelength of the second resonance wavelength band does not overlap with the first absorption wavelength band and overlaps with the second absorption wavelength band.

(Appendix 14)
The photoelectric converter according to claim 7, wherein the energy difference matches a photon energy of light in the composite resonance wavelength band before or after modulation by the modulation unit.

(Appendix 15)
The photoelectric converter according to appendix 14, wherein the light in the composite resonance wavelength band is light having a maximum wavelength in the composite resonance wavelength band.

(Appendix 16)
The light absorption layer includes a first quantum dot and a second quantum dot, and a first energy difference between energy levels of electrons bound to the first quantum dot and a first complex resonance of the complex resonator system The photon energy of the light in the wavelength band matches,

A second energy difference between energy levels of electrons bound to the second quantum dots and a photon energy of light in a second composite resonance wavelength band of the composite resonator system match;
16. The complex resonance wavelength band is modulated from the first complex resonance wavelength band to the second complex resonance wavelength band by modulation of the resonance wavelength band of the first optical resonator. The photoelectric converter as described.

(Appendix 17)
The maximum wavelength of the first composite resonance wavelength band overlaps with the first absorption wavelength band corresponding to the first energy difference and does not overlap with the second absorption wavelength band corresponding to the second energy difference,
The photoelectric converter according to appendix 16, wherein a maximum wavelength of the second composite resonance wavelength band does not overlap with the first absorption wavelength band and overlaps with the second absorption wavelength band.

(Appendix 18)
The photoelectric converter according to claim 8, wherein the light absorption layer includes an antireflection film on a side of the resonator type filter.

(Appendix 19)
The photoelectric converter according to claim 9, wherein the semiconductor substrate and the light absorption layer form one element with the first reflecting mirror or the second reflecting mirror.

(Appendix 20)
An illuminance meter, a luminance meter, a photometer, or a photometric device comprising a light detection unit having the photoelectric converter according to any one of claims 1 to 9 and appendices 11 to 19.

(Appendix 21)
An imaging device comprising an imaging unit having an array in which the photoelectric converters according to any one of claims 1 to 9 and appendices 11 to 19 are arranged.

(Appendix 22)
A focus adjustment unit and a direction control that receive an information based on light having a first wavelength, the imaging device including a photodetection unit including the photoelectric converter according to any one of claims 1 to 9 and appendices 11 to 19. A first adjustment unit that is an optical tracking unit, an automatic tracking unit, an optical axis adjustment unit, or a camera shake correction unit, and a focus adjustment unit that receives information based on light of the second wavelength, a direction control unit, an automatic tracking unit, an optical axis adjustment unit or A second adjustment unit that is a camera shake correction unit, the adjustment function of the second adjustment unit is different from that of the first adjustment unit, and the light detection unit receives light of the first and second wavelengths.

(Appendix 23)
A light emitting body, a light guide body, a light distribution body, an optical lens, or an eye inspection device, comprising the light detection unit having the photoelectric converter according to any one of claims 1 to 9 and appendices 11 to 19.

(Appendix 24)
A radiation thermometer or a temperature measuring device comprising a photodetecting unit having the photoelectric converter according to any one of claims 1 to 9 and appendices 11 to 19.

(Appendix 25)
An air blower, an air conditioner, a heater, a cooker, a thermostat, a refrigerator, or a freezer comprising the temperature measuring device according to appendix 24 and a temperature adjusting unit that receives information on the temperature measured by the temperature measuring device.

(Appendix 26)
A fire alarm device or a leak detection device, comprising: the temperature measurement device according to attachment 24; and a determination unit that receives information about a temperature measured by the temperature measurement device.

(Appendix 27)
A gas detection device comprising a photodetection unit having the photoelectric converter according to any one of claims 1 to 9 and appendices 11 to 19, and further comprising a determination unit that receives information on a gas detected by the gas detection device. Fire alarm device or leak detection device.

(Appendix 28)
A photoelectric converter according to any one of claims 1 to 9 and appendices 11 to 19, comprising a photodetection unit shared by a temperature measurement device and a gas detection device, wherein the temperature measurement device is derived from a solid surface temperature. Receiving information based on light of a first wavelength, the gas detection device receives information based on light of a second wavelength derived from a structure of gas molecules, and the light detection unit receives information of the first and second wavelengths. Fire alarm device or leak detection device that receives light.

(Appendix 29)
An optical reader for a wireless communication device or a non-contact type card, comprising a light receiving unit having the photoelectric converter according to any one of claims 1 to 9 and appendices 11 to 19.

(Appendix 30)
A distance measuring device or a position determining device comprising a light receiving unit for reflected light, comprising the photoelectric converter according to any one of claims 1 to 9 and appendices 11 to 19.

(Appendix 31)
An optical reading device for bills or securities having a light receiving part for transmitted light or reflected light, comprising the photoelectric converter according to any one of claims 1 to 9 and appendices 11 to 19.

(Appendix 32)
The information based on the light receiving part of the transmitted light or the reflected light and the light generated or attenuated by the first molecule or atom, comprising the photoelectric converter according to claim 1. And a second detector for receiving information based on light generated or attenuated by the second molecule or atom, wherein the light receiver is the first and second molecule or atom. A liquid, gas, living body, fruit and vegetable, food, or pharmaceutical analysis device that receives light generated or attenuated by the above.

(Appendix 33)
A photoelectric switch provided with the light-receiving part which has a photoelectric converter in any one of Claims 1-9 and Additional remarks 11-19.

(Appendix 34)
A night-vision device, an obstacle detection device, an exploration device, or a target display device, comprising a light-receiving unit having the photoelectric converter according to any one of claims 1 to 9 and appendices 11 to 19.

(Appendix 35)
An alarm device for an intruder or an antitheft device, comprising a detection unit having the photoelectric converter according to any one of claims 1 to 9 and appendices 11 to 19.

DESCRIPTION OF SYMBOLS 100 Photoelectric converter 101 Semiconductor substrate 102 Light absorption layer 103 Light modulation layer 106 Resonator (optical resonator) 200 Infrared detector (light detector)
202 Lower contact layer 205 Upper contact layer 208 Voltage source (voltage source for detection) 209 Ammeter 214 Lower electrode (input unit) 215 Upper electrode (input unit)
216 Voltage source (voltage source for modulation) 220 Photoelectric conversion layer 304 Infrared light (light) 305 Infrared light (light)
400 First absorption wavelength band 401 Second absorption wavelength band 600 Photoelectric converter 601 Semiconductor substrate 602 Light absorption layer 603 Light modulation layer 606 First resonator (first optical resonator) 607 Second resonator (second light) Resonator)
700 First Absorption Wavelength Band 701 Second Absorption Wavelength Band 800 Photoelectric Converter 806 Resonator Type Filter 814 Lower Electrode (Input Portion) 815 Upper Electrode (Input Portion)
816 Voltage source (modulation voltage source) 900 Photoelectric converter 903 Drive unit 904 First reflecting mirror 905 Second reflecting mirror 906 Resonator (optical resonator)
914 Electrode (input unit) 915 Electrode (input unit)

Claims (10)

A semiconductor substrate, a light absorption layer, an optical resonator, and a modulation means for modulating a resonance wavelength band of the optical resonator;
The light absorption layer has one or more quantum confinement structures selected from the group consisting of quantum dots, quantum wires, and quantum wells,
The modulation means includes an input unit that receives an applied voltage from a voltage source ;
The modulation means comprises a light modulation layer having one or more quantum confinement structures selected from the group consisting of quantum dots, quantum wires, and quantum wells,
The semiconductor substrate, the light absorption layer, the optical resonator, and the light modulation layer constitute one element.
Photoelectric converter.   The energy difference between the energy levels of electrons bound to the quantum confinement structure matches the photon energy of light in the resonance wavelength band before or after modulation by the modulation means. Photoelectric converter.   The photoelectric converter according to claim 1, wherein the light absorption layer includes a first quantum dot and a second quantum dot having a size, shape, or material different from that of the first quantum dot. The light absorption layer includes a photoelectric conversion layer having the first quantum dots and the second quantum dots, and two contact layers,
The photoelectric conversion layer is located between the two contact layers,
The two contact layers are located outside the photoelectric conversion layer ,
No other contact layer is located between the two contact layers,
The photoelectric converter according to claim 3. A first energy difference between energy levels of electrons bound to the first quantum dots and a photon energy of light in a first resonance wavelength band of the optical resonator match;
A second energy difference between energy levels of electrons bound to the second quantum dots and a photon energy of light in a second resonance wavelength band of the optical resonator match;
The first absorption wavelength band corresponding to the first energy difference and the second absorption wavelength band corresponding to the second energy difference are discrete,
The photoelectric converter according to claim 3 or 4, wherein the modulation unit modulates the resonance wavelength band from the first resonance wavelength band to the second resonance wavelength band. It includes the optical resonator by the first optical resonator,
Further comprising a second optical resonator of the composite resonator system together with the first optical resonator,
The composite resonator system, arising a complex resonance wavelength band that is present commonly in resonant wavelength band of the first optical resonator and a second optical resonator,
The photoelectric converter according to claim 1 . A semiconductor substrate, a light absorption layer, a first optical resonator, a second optical resonator constituting a composite resonator system together with the first optical resonator, and a resonance wavelength of the first optical resonator; A modulation means for modulating the band;
The light absorption layer has one or more quantum confinement structures selected from the group consisting of quantum dots, quantum wires, and quantum wells,
The modulation means includes an input unit that receives an applied voltage from a voltage source;
The composite resonator system generates a composite resonance wavelength band that exists in common in the resonance wavelength bands of the first optical resonator and the second optical resonator.
Photoelectric converter. The light absorption layer includes a first quantum dot and a second quantum dot, and a first energy difference between energy levels of electrons bound to the first quantum dot and a first complex resonance of the complex resonator system The photon energy of the light in the wavelength band matches,
A second energy difference between energy levels of electrons bound to the second quantum dots and a photon energy of light in a second composite resonance wavelength band of the composite resonator system match;
The photoelectric conversion according to claim 6 or 7, wherein the composite resonant wavelength band is modulated from the first composite resonant wavelength band to the second composite resonant wavelength band by modulation of a resonant wavelength band of the first optical resonator. vessel. The maximum wavelength of the first composite resonance wavelength band overlaps with the first absorption wavelength band corresponding to the first energy difference and does not overlap with the second absorption wavelength band corresponding to the second energy difference,
9. The photoelectric converter according to claim 8, wherein a maximum wavelength of the second composite resonance wavelength band does not overlap with the first absorption wavelength band and overlaps with the second absorption wavelength band. A semiconductor substrate, a light absorption layer, an optical resonator, and a modulation means for modulating a resonance wavelength band of the optical resonator;
The light absorption layer has one or more quantum confinement structures selected from the group consisting of quantum dots, quantum wires, and quantum wells,
The modulation means includes an input unit that receives an applied voltage from a voltage source;
The modulation means comprises a light modulation layer having one or more quantum confinement structures selected from the group consisting of quantum dots, quantum wires, and quantum wells,
The semiconductor substrate, the light absorption layer, the optical resonator, and the light modulation layer constitute one element.
A photoelectric converter; and modulating voltage source connected to said input unit; a detection voltage source connected to said light absorbing layer; and ammeter connected to said light absorbing layer; photodetector comprising, using A light detection method for detecting light, comprising:
A modulation step of modulating the resonance wavelength band by generating or changing an applied voltage to the modulation means in the modulation voltage source;
A light receiving step of receiving light with the photoelectric converter;
An optical resonance step of resonating the light in the optical resonator;
A light absorption step of absorbing the resonated light in the quantum confinement structure;
A photoelectric conversion step in which a voltage is applied to the light absorption layer by the voltage source for detection to photoelectrically convert the absorbed light in the light absorption layer to generate a current;
And a detection step of detecting current with the ammeter.

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